The Underaged Detectives
by hath57
Summary: It was the first day at school for Sherlock Holmes. After meeting Watson, he soon finds he has an unbreakbable bond with him. With missile plans, murderer taxi drivers, prostitute women... and school. Slow moving Sherlock/John, teen!AU.
1. Chapter 1 A Study In Scarlet School

**Chapter One- A Study In Scarlet Secondary School**

John Watson, aged 15 years, 6 months and 25 days, shifted about violently in his bed. One name was on the tip of his tongue.

His father's name.

He had been dead for a few years now, and the nightmares should've stopped coming.

But they were becoming clearer, haunting him further.

His father had been in the army. He had excelled, and made John and his family proud. His father could get through anything unscathed.

Except the bullet that shot through his brain, burst his cerebal cortex and killed him in two seconds.

John woke with a start, panting heavily. He was sweating as he saw his dreams' ever resent approach to what his father's death would've looked like.

He couldn't do or say anything. His brain didn't seem to respond to the actions that he wanted to carry out. So he just sat there, terror through his mind, for hours on end until sunlight filled the room.

****

John didn't pay any attention to the teasing or the bullying that morning as he strolled silently into lesson, rucksack over his shoulder. He didn't mind that someone was flicking- whatever that purple stuff was at him. He was too preoccupied with terror.

But there was more. More than just simple fear. There was a whole other layer to this. A layer of longing. He wasn't sure why, but he longed to be the one in that khaki uniform, gun over back. He longed to be the one who was running through dangerous terrain without a care in the world.

He was awoken from his thoughts by a new arrival. He was dressed in a sharp, elegant blue coat, the same ordinary suits they were forced to wear, a blue scarf and black boots. His hear was frizzy, and his cheekbones jutted out slightly, like they were trying to force their way out of his skin.

The boy sat down next to John, and John smiled awkwardly at him as he threw off his coat and scarf. The boy noticed this and just grunted, taking out his pencil case from his bag.

"Boys," The voice of the Maths teacher ran out. "We have a new student today. Sherlock Holmes." People started sniggering at his name, but Sherlock merely rolled his eyes and closed his hands around a small metal object in his pocket, taking it out to reveal a small patry dish labelled 'Class A Drug Sample- If released in air will react immediately. No explosive consequences, and the smell will immediately cause people to feel the drug. Warning- do not take if allergic to any of the following kinds-' There was a long list that Sherlock honestly couldn't be bothered reading. Sherlock slumped it into his pocket, not listening to the maths' teachers ramblings about life at Scarlet School, and took out his iPhone, unlocking it to see a text from his brother, Mycroft.

_You're not aloud to read texts in lessons. I know you are doing so now, you don't care about the rules. Not that you knew them._

_Just letting you know._

_Hope they don't take your phone._

_MH_

Sherlock rolled his eyes and prepared to explain to his teacher why he had it out, but he didn't even notice him take it out. He was facing the whiteboard, still rambling about how 'lovely' the place was. Then, his phone buzzed again and he picked it out, eyes rolling in preparation.

_Got something you might like to see. And listen, you're an underaged smoking detective, so tell me everything or you'll be in a cell before I can say 'piss off'._

_Meet me at 5 at Brixton, no. 3 Lauriston Gardens._

_Just so you know, Anderson will be there._

_Lestrade_

Sherlock's grin spread across his face, and he prepared for the boring Maths lesson that he would miss. He was looking forward to something. About time to.

Sherlock bit into his Panini, ignoring the sniggers and looks he was getting. He smiled eagerly as his phone buzzed, hoping it would be a text from Lestrade.

No such luck. A message from Mycroft flashed up, reading:

_Urgent. Missile plans issued to Bruce Partington stolen. Bruce Partington found dead on train tracks. Peculiar and rather dangerous business that may satisfy you._

_Come at once. Battersea train station. Have already bribed your teachers into letting you out. A helicopter will pick you up from the roof when you're ready. Which has to be now._

_MH_

Sherlock sighed, his fingers dancing across the keyboard, not noticing a boy sit down opposite him.

_I already have a case, Mycroft._

_SH_

Almost immediately, another text flashed up from his brother.

_Yes. No. 3 Lauriston Gardens, I saw the message._

_MH_

Sherlock's fingers danced again.

_How?_

_SH_

_I hacked your phone ages ago, Sherlock. Give me some credit._

_MH_

_I am changing the settings as soon as I can._

_SH_

_And I'll hack it again. Don't think you can outwit me, dear brother. It will never work._

_MH_

_I already have, countless times. It is how I know that you're shagging your assistant, Amanda was it?_

_SH_

_Lucy, Sherlock._

_MH_

_Is that even her real name?_

_SH_

_No._

_MH_

Sherlock inwardly sighed, finally noticing John Watson sitting across from him. Awkward silence ensued, before Sherlock spoke up.

"Look, you might aswell sit somewhere else. I'm a highly functioning sociopath, you're a would-be Army Doctor. I'm not normal, you are. Go and talk to actual people."

"You are a person." John murmured.

"Not in your sense. Do most people solve crimes at my age?"

"You what?" John asked, eyes wide.

"As I said, highly functioning sociopath."

"Wait… With the police? You're a police officer _already_?"

"Consulting Detective. It's a long story and you probably would be interested, but I'm waiting for my brother's helicopter."

With that, Sherlock walked out, John following him.

"Brother." Mycroft nodded, then frowned as he saw John. The helicopter ride had taken twenty two minutes, and Sherlock surprisingly hadn't put up a fuss. John smiled awkwardly, and Mycroft murmured into Sherlock's ear "You didn't say you were bringing a… _pet_..."

"He's not with me." Sherlock hissed back.

"Yes I am." John hissed at him.

"I didn't _ask _you to come." Sherlock said icily.

"You didn't put up a fuss about me climbing into a private helicopter."

"Well, it's not like you're anything like the infamous Moriarty."

"Who?"

"Heard about him a while back, he pulled the strings in a few of my cases."

"Who is he?"

"No idea."

"You never met him?"

"Look…" Sherlock hissed. "Why do you _care_? Why are you actually here?"

"You fascinate me."

"Oh great, a fan. Just what I need."

"You don't like attention?"

"No!" Sherlock replied gruffly. "It gets in the way."

"Children…" Mycroft hissed. "If you could be so kind as to follow." Mycroft said as he abruptly turned and walked into Battersea, looking at the dead body on the train tracks. Sherlock pulled out a small rectangular glass and immediately pressed it up against places on the body, examining every inch. After about thirty seconds, he stood up.

"He wasn't killed here. There was no blood on the train tracks, but there's a huge gash in his head. Look over there, the train tracks, every few seconds, twist to go a different direction. This is delightfully simple because there was no train ticket on the body, and there was no oyster card or cash. It's so obvious. The body was dumped on top of a train, and was probably far away from the murderer before the train tracks twisted. So, murdered in a completely different place, and I know where. Southwark. And I know who did it, or who most likely did it. His only friend, this man." He held up a photograph. "Who else could've done it? Who else could he trust with the knowledge of missile plans assigned to him by the british government? Mycroft, tell your men to find this man. He'll have the memory stick."

"Bloody… wow." John exclaimed. "That was extraordinary, it was quite extraordinary."

"That's not what people usually say."

"What do people usually say?"

"Piss off." John and Sherlock allowed themselves to chuckle at that, and unbeknownst to John, Sherlock was warming greatly to Watson in the short time he'd known him.

"Brother, your helicopter awaits." Mycroft gestured to it, and Sherlock walked back with John.


	2. Chapter 2 No 3 Lauriston Gardens

**Chapter Two- No. 3 Lauriston Gardens**

The rest of the day was slow, but it was still made better by the thought that soon there'd be another mystery to solve.

"You don't mind that I'm a freak that can tell your life story for you?" Sherlock asked John as he walked out of the gates at the end of the day.

"No. You're brilliant."

"Thanks." Sherlock smiled, blushing. "Listen… I'm going to Brixton now to meet with some of the police, they have a case to solve. Not that exciting probably to you, but I could do with some help."

He already knew what John would say.

"Freak." Sally Donovan acknowledged as she pulled up the yellow-and-black tape police tape measure.

"Sergeant Donovan." Sherlock grimaced as he entered, John following after him.

"Woah, woah, woah…" Lestrade exclaimed as he gestured to John. "Who is _he_?"

"This is John Watson, he's a…" Sherlock searched his mind for the right word. "Friend."

"Friend? How did you get a friend?" Sally asked from behind. "Did he follow you home?" Sally laughed, and Sherlock and John both found themselves rolling their eyes.

"Sherlock." Lestrade said firmly. "I'm breaking every rule letting you in here, let alone…"

"Yes, because you need me. Aside from the constrictions of my age, I am the greatest asset you could ever have. And you _know _you need me."

"Yes I do." Lestrade sighed. "God help me."

"God help you." Anderson agreed as he emerged from the door. "This is a crime scene, kid. I don't want it contaminated. Are we clear on that?"

"Quite clear." Sherlock did a mock salute. "How long is your wife away for?"

"Oh, don't pretend you worked that out, someone told you that."

"Your deodorant told me that."

"My deodorant?"

"It's for men."

"Well of course it is, I'm wearing it!"

"So is Sergeant Donovan." Sherlock said, and Anderson stared at him in horror, blushing heavily."

"Whatever you're trying to imply…"

"I'm not implying anything, I'm sure you just invited her over and she just _happened _to spend the night. And I'm assuming she scrubbed your floors judging by the state of her knees." Sherlock smiled wickedly, walking up to the house. John fought back a glance at Sally's knees as he followed him.

John was dressed in a blue containment outfit along with everyone else except Sherlock as they entered the room in question, revealing a face down body. It was a woman's, her clothes all an alarming shade of pink that John didn't even know had existed. Sherlock repeated his ritual from earlier, his glass catching everything around him. The one thing which was obvious to everyone was the letters 'RACHE' scratched on the floor. As Sherlock stood up, Anderson's voice sounded from the doorway.

"German, then. 'Rache', German for 'Revenge'. She could be trying to tell us…"

"Yes, thank you for your input." Sherlock snarled as he slammed the door shut infront of Anderson, leaving just Sherlock, Lestrade, John and three other slightly less annoying detectives. "Now, then. She's damp up the legs and the lower section of her back and no-where else, only splash marks from a suitcase she must have been carrying with her right hand. More splashes down her right leg than her left meaning she was carrying it with that hand. Now, her wedding ring. It's dirty, you can see that. But unlike all of her other jewellery, everything else is clean. State of her marriage right there, the only polishing it gets its when she works it off her finger, the underside being nearly completely clean. She wrote 'RACHE' on the floor. She was writing a loved one's name 'RACHEL' rather than an angry note in German. Her clothes are brightly pink, showing us that she's a journalist. It appears she commited suicide, like the others from last year. So another serial suicide. You probably heard of it John, the suicides that were clearly linked somehow. Obviously work of a serial killer. Love those."

"You said suitcase… There wasn't one." Lestrade said.

"What?" Sherlock asked, eyes wide. "Say that again."

"There was no suitcase!"

"Sherlock?" John asked as Sherlock bounded down the steps towards the door.

"Serial Killers are always hard, always have to wait for them to make a mistake."

"We can't just wait!" Lestrade exclaimed.

"Oh, we're done waiting. The game is on."

"How?" Lestrade asked.

"Euston, we have a mistake." Sherlock smiled as he walked with John to the door.

"What is the mistake? What?"

"Pink!" Sherlock called as he and John walked out of the house.

"Right… What are we doing?" John asked the boy who he now felt like he had known for a long time. They were in the middle of a waste dump, Sherlock rummaging through rubbish.

"Suitcase. It has to be somewhere…" Sherlock said as he threw around rubbish, before finally finding the pink case. He smiled, throwing it open and rummaging through the contents, before smiling at his discovery.

"What?" John asked.

"No phone, John. A woman like this would have a phone. It was obvious she didn't check into a hotel. It's not in her case, it's not in her coat. Where is it?"

"The murderer has the phone…" John realised.

"Exactly." Sherlock smiled as he took out his iPhone, held out a piece of paper with her address and phone number on she had put in the front of her suitcase, and began to type:

_What happened in Lauriston Gdns? I must have blacked out. 22 Northumberland Street. Please come._

Sherlock waited a minute, before his phone rang. "Now, the murderer receives a text which can only be from her. An innocent man would ignore it. A guilty man would panic." Sherlock smiled as he tossed the suitcase back in the rubble and ran towards a taxi. "You coming?"

"I'm just a kid, and I'm helping you to solve a murder case?"

"Yeah, but you know you're enjoying this. I promised danger, and here you are. You see, you don't just feel scared at the prospect of war. You long for it. And here it is."

"I…" John couldn't think of what to say. Instead they both piled into the taxi, the cab driving them to Northumberland Street.

Sherlock and John were waiting on a street corner, eyes scanning for a taxi.

"John. We're looking for something that goes by unnoticed everyday. We willingly walk in, not caring where we're taken. The invisible car. The London cab!" Sherlock beamed. Finally, after five minutes, John managed to speak.

"Do you have a girlfriend?" John asked, surprising Sherlock.

"Um… Not really my area." Sherlock said, cheeks flushing.

"Oh. _Oh_… Do you have a boyfriend? Which is fine, by the way."

"I know it's fine." Sherlock snapped.

"Oh. So, you don't then."

"No."

"Good."

"Why is that good?"

"It just is."

They stood in uncomfortable silence before the cab came into view, and they both ducked behind a recycling bin. Sherlock retrieved a bottle of lucosade from his bag and threw it over his face, before gesturing to John to do the same. John reluctantly did it, and gasped at the sting.

"Mixed with alcohol. Sorry, has to seem real. We have to pretend to be drunk. Got it?"

"Got it." John nodded, rubbing his face. Finally, they stood and stumbled awkwardly towards the taxi, knocking on the window. The driver waved them off.

"Come on…" Sherlock pleaded in a slur. "221B Baker Street."

"No. I'm off shift and I don't do drunks." The driver snapped.

"221B…" Sherlock mumbled, before disappearing around the back of the car and ringing the dead woman's number.

"Hello?" The driver asked into it, worried.

"How do you make them take the poison?" Sherlock asked in a sinister sober voice.

"What?" The driver asked.

"I said, how do you make them take the poison?" Sherlock asked, grabbing the driver by the lapels violently, John helping him after a wide-eyed beat.

"Who are you?" He croaked.

"Sherlock Holmes and John Watson." Sherlock murmured. The driver merely smiled, and then Sherlock realise why. The pair collapsed onto their knees, trying desperately to get into the car. But the driver merely threw them into the back seat of his car.

They lost consciousness in about ten seconds.

Sherlock's eyes snapped open, to reveal an Edwardian style house, laden with pictures of him, with his mother, father, and Mycroft. It was his house.

"Hope you don't mind." The Taxi Driver sounded from behind. "You gave me your address."

"Hu-Who are you?" Sherlock asked in a slur, the drug still in his system. "My-Mycroft…" Sherlock tried to call.

"Your family aren't here, don't bother trying. There was an unexpected emergency to do with a family member. I sent em to the hospital."

"You phycopath." Sherlock gasped.

"You can talk." He sneered. "You don't want to try to get up, you'll be as weak as a kitten for at least an hour. I could do anything I wanted to you right now Mr Holmes. Anything at all. But don't worry. I'm only gonna kill ya." The driver dragged him over to a chair, dropping him down roughly. "Get yourself comfy. I want your best game."

"My best _what_?"

"Found your website. Very impressive for someone of your age. _The Science Of Deduction_, now that is proper thinking. Your friend will be up soon, I gave him a bit of an extra dose so we could have a bit of a chat before the game. You see, isn't the world so _stupid_?"

"Oh, I see. So you're a proper genius too?" Sherlock rolled his eyes.

"Don't look it, do I? The cabbie. The old cabbie. You see, being a cabbie is the best cover for a murderer. I'm surprised no-one else has done this."

"Not everyone's insane. How did you do it? Kill all those people?"

"Oh, Mr Holmes." The Driver chuckled. "You're gonna love this. But let's wait until your friend wakes up, eh? Time for a chat. How long have you been doing what you do?"

"A few years."

"Impressive stuff. You see, you're brain is a gift aswell as a curse."

"God, how cryptic can you get?"

"No, Mr Holmes. You're clever, but not clever enough. This is just too easy…" The Driver moaned. "You haven't worked it out. How I did it. The Sherlock Holmes I pictured already knew."

Before Sherlock could retort, John's eyes snapped open, taking in his barren surroundings.

"Where…" John began.

"He's awake then." The Driver smiled creepily. "Good. Time to play." The Driver helped John into a chair, and then brought out two bottles of pills. "There's a good pill and a bad pill. Take the good pill you live, take the bad pill you die. Oh, this is genius. This really is brilliant. Normally people go against me. But _now_, I can pit you against eachother. Oh, this is gonna be brilliant. Go on then, make your moves."

"Sherlock… What do we do?" John asked, shaking with fear.

"I'm sorry, John. I shouldn't have dragged you into this."

"What do we do?" John repeated.

"Right… Look for differences, look for differences…" Sherlock spent two uncomfortable minutes staring in silence at the pills, before slamming his hand onto the table. "They're identical in every way! Uh…" Sherlock ruffled his hair. Then, his eyes lit up. "You've made a mistake, cabbie." Sherlock stood up, before falling down again. The Driver merely chuckled, and Sherlock still had a mask of triumph on his face. "You brought me into my own house. First mistake. Second mistake is that you didn't check under the chairs for either the gun or the emergency police caller button. Third mistake…" Sherlock brought out the gun from under a chair. "The gun you have in your pocket is a candle lighter." Sherlock cocked the gun and held it up at the driver. "What if I just killed you now?"

"Mr Holmes, you'd miss out on the game." The Driver sneered. "And how you love a game."

"Not with John."

"Oh, I see. Protecting him. What if it was between you and me?" The Driver lifted John from a chair and dumped him onto the floor, before sitting down himself. "Have you chose a pill? Come on, Mr Holmes. Be a little bit fun." Sherlock stared, before dumping the gun down and sitting down again at the table.

"You can't be serious!" John exclaimed.

"I'm very serious, John."

"You'd kill yourself to make yourself look clever?"

"I…" Sherlock didn't answer at this, and picked up one of the pills.

"Oh…" The Driver smiled. "How interesting. So then. This is the end of the game." The Driver picked up the other pill and held it upwards, Sherlock mirroring him. "We have to worry, or the police will intervene with the game. Come on, Mr Holmes. Time to play. Time to end the game."

"Wait." Sherlock stopped him.

"What?"

"You would risk yourself several times to play a game? You're dying. Aren't you."

"Aneurism. Right in here. Any breath could be my last. I get paid for every murder, a guy called Moriarty pays me. I get rich. I live in luxury before I die. It's a brilliant game of chess. Now, let's do this." They both raised the pills to their mouths, Sherlock ready to take a bite when…

A hole pierced the Driver's chest, and he collapsed to the floor. Sherlock turned abruptly, dropping the pill, to see John on the floor, holding Sherlock's gun.

"John." Sherlock whispered. "You killed him."

"I…" John whispered, staring at the gun. "I know."

Lestrade and his team arrived in three minutes. Sherlock covered up what John did and said that he did it, to avoid John having a court case.

John left afterwards, terrified of the night's events.


End file.
